[PATCH] x86/shadow: don't leave trace record field uninitialized

[Jan Beulich <jbeulich@xxxxxxxx>]

The emulation_count field is set only conditionally right now. Convert
all field setting to an initializer, thus guaranteeing that field to be
set to 0 (default initialized) when GUEST_PAGING_LEVELS != 3.

While there also drop the "event" local variable, thus eliminating an
instance of the being phased out u32 type.

Coverity ID: 1598430
Fixes: 9a86ac1aa3d2 ("xentrace 5/7: Additional tracing for the shadow code")
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -2093,20 +2093,18 @@ static inline void trace_shadow_emulate(
             guest_l1e_t gl1e, write_val;
             guest_va_t va;
             uint32_t flags:29, emulation_count:3;
-        } d;
-        u32 event;
-
-        event = TRC_SHADOW_EMULATE | ((GUEST_PAGING_LEVELS-2)<<8);
-
-        d.gl1e = gl1e;
-        d.write_val.l1 = this_cpu(trace_emulate_write_val);
-        d.va = va;
+        } d = {
+            .gl1e = gl1e,
+            .write_val.l1 = this_cpu(trace_emulate_write_val),
+            .va = va,
 #if GUEST_PAGING_LEVELS == 3
-        d.emulation_count = this_cpu(trace_extra_emulation_count);
+            .emulation_count = this_cpu(trace_extra_emulation_count),
 #endif
-        d.flags = this_cpu(trace_shadow_path_flags);
+            .flags = this_cpu(trace_shadow_path_flags),
+        };
 
-        trace(event, sizeof(d), &d);
+        trace(TRC_SHADOW_EMULATE | ((GUEST_PAGING_LEVELS - 2) << 8),
+              sizeof(d), &d);
     }
 }
 #endif /* CONFIG_HVM */